The proposed studies deal with the dynamics of plasma membrane structure and function of normal and tumor cells in cell culture. The plasma membranes of undifferentiated and differentiated neuroblastoma cells will be isolated and their enzymatic composition compared. In other studies the profiles of polypeptides, glycoproteins and phopholipids of these membranes will be established for both types of cells. In addition, the polypeptides accessible at the outer and inner surfaces of the plasma membrane will be investigated through the use of selective nonpermeant labeled probes. Further studies will deal with the quantitation of the plasma membrane receptors for concanavalin A and phytohaemagglutinin-P, and the characterization of various kinetic parameters of the binding of lectin to its cell-surface receptors.